new file mode 100644
--- /dev/null
+++ b/.cargo/.gitignore
@@ -0,0 +1,1 @@
+config

new file mode 100644
--- /dev/null
+++ b/js/src/.gitignore
@@ -0,0 +1,1 @@
+target/

new file mode 100644
--- /dev/null
+++ b/js/src/Cargo.lock
@@ -0,0 +1,38 @@
+[root]
+name = "mozjs_sys"
+version = "0.0.0"
+dependencies = [
+ "libc 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libz-sys 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "gcc"
+version = "0.3.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "libc"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "libz-sys"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "gcc 0.3.35 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "pkg-config"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[metadata]
+"checksum gcc 0.3.35 (registry+https://github.com/rust-lang/crates.io-index)" = "91ecd03771effb0c968fd6950b37e89476a578aaf1c70297d8e92b6516ec3312"
+"checksum libc 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)" = "408014cace30ee0f767b1c4517980646a573ec61a57957aeeabcac8ac0a02e8d"
+"checksum libz-sys 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "40f2df7730b5d29426c3e44ce4d088d8c5def6471c2c93ba98585b89fb201ce6"
+"checksum pkg-config 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "8cee804ecc7eaf201a4a207241472cc870e825206f6c031e3ee2a72fa425f2fa"

new file mode 100644
--- /dev/null
+++ b/js/src/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "mozjs_sys"
+version = "0.0.0"
+authors = ["Mozilla"]
+links = "mozjs"
+build = "build.rs"
+
+[features]
+debugmozjs = []
+promises = []
+
+[lib]
+name = "mozjs_sys"
+path = "lib.rs"
+
+[dependencies]
+libc = "0.2"
+libz-sys = "1.0"

new file mode 100644
--- /dev/null
+++ b/js/src/build.rs
@@ -0,0 +1,53 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+use std::env;
+use std::process::{Command, Stdio};
+
+fn main() {
+    let out_dir = env::var("OUT_DIR").expect("Should have env var OUT_DIR");
+    let target = env::var("TARGET").expect("Should have env var TARGET");
+
+    let js_src = env::var("CARGO_MANIFEST_DIR").expect("Should have env var CARGO_MANIFEST_DIR");
+
+    env::set_current_dir(&js_src).unwrap();
+
+    let variant = if cfg!(feature = "debugmozjs") {
+        "plaindebug"
+    } else {
+        "plain"
+    };
+
+    let python = env::var("PYTHON").unwrap_or("python2.7".into());
+    let mut cmd = Command::new(&python);
+    cmd.args(&["./devtools/automation/autospider.py",
+               "--build-only",
+               "--objdir", &out_dir,
+               variant])
+        .env("SOURCE", &js_src)
+        .env("PWD", &js_src)
+        .env("AUTOMATION", "1")
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit());
+    println!("Running command: {:?}", cmd);
+    let result = cmd
+        .status()
+        .expect("Should spawn autospider OK");
+    assert!(result.success(), "autospider should exit OK");
+
+    println!("cargo:rustc-link-search=native={}/js/src", out_dir);
+
+    if target.contains("windows") {
+        println!("cargo:rustc-link-lib=winmm");
+        println!("cargo:rustc-link-lib=psapi");
+        if target.contains("gnu") {
+            println!("cargo:rustc-link-lib=stdc++");
+        }
+    } else {
+        println!("cargo:rustc-link-lib=stdc++");
+    }
+
+    println!("cargo:rustc-link-lib=static=js_static");
+    println!("cargo:outdir={}", out_dir);
+}

new file mode 100644
--- /dev/null
+++ b/js/src/lib.rs
@@ -0,0 +1,2 @@
+extern crate libz_sys;
+

--- a/js/src/make-source-package.sh
+++ b/js/src/make-source-package.sh
@@ -96,16 +96,17 @@ case $cmd in
     ${MKDIR} -p ${tgtpath}/.cargo
     cp -pPR ${TOPSRCDIR}/.cargo/config.in ${tgtpath}/.cargo
 
     # put in js itself
     cp -pPR ${TOPSRCDIR}/mfbt ${tgtpath}
     cp -p ${SRCDIR}/../moz.configure ${tgtpath}/js
     cp -pPR ${SRCDIR}/../public ${tgtpath}/js
     cp -pPR ${SRCDIR}/../examples ${tgtpath}/js
+    cp -pPR ${SRCDIR}/../rust ${tgtpath}/js
     find ${SRCDIR} -mindepth 1 -maxdepth 1 -not -path ${STAGING} -a -not -name ${pkg} \
         -exec cp -pPR {} ${tgtpath}/js/src \;
 
     cp -pPR \
         ${TOPSRCDIR}/python \
         ${tgtpath}
     ${MKDIR} -p ${tgtpath}/dom/bindings
     cp -pPR \

--- a/taskcluster/ci/spidermonkey/kind.yml
+++ b/taskcluster/ci/spidermonkey/kind.yml
@@ -63,16 +63,31 @@ jobs:
                 - nsprpub/**
                 - python/**
                 - taskcluster/moz.build
                 - testing/mozbase/**
                 - test.mozbuild
                 - toolkit/mozapps/installer/package-name.mk
                 - toolkit/mozapps/installer/upload-files.mk
 
+    sm-mozjs-sys/debug:
+        description: "Build js/src as the mozjs_sys Rust crate"
+        index:
+            job-name:
+                gecko-v2: sm-mozjs-sys-debug
+        treeherder:
+            symbol: SM-tc(mozjs-crate)
+        run:
+            using: spidermonkey-mozjs-crate
+            spidermonkey-variant: plain
+        run-on-projects:
+            - integration
+            - release
+            - try
+
     sm-plain/debug:
         description: "Spidermonkey Plain"
         index:
             job-name:
                 buildbot: sm-plain
                 gecko-v2: sm-plaindebug-debug
         treeherder:
             platform: linux64/debug

new file mode 100755
--- /dev/null
+++ b/taskcluster/scripts/builder/build-sm-mozjs-crate.sh
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+set -xe
+
+source $(dirname $0)/sm-tooltool-config.sh
+
+# Ensure that we have a .config/cargo that points us to our vendored crates
+# rather than to crates.io.
+cd "$SRCDIR/.cargo"
+sed -e "s|@top_srcdir@|$SRCDIR|" < config.in | tee config
+
+cd "$SRCDIR/js/src"
+
+export PATH="$PATH:$TOOLTOOL_CHECKOUT/cargo/bin:$TOOLTOOL_CHECKOUT/rustc/bin"
+export RUST_BACKTRACE=1
+
+cargo build --verbose --frozen --features debugmozjs
+cargo build --verbose --frozen

--- a/taskcluster/taskgraph/transforms/gecko_v2_whitelist.py
+++ b/taskcluster/taskgraph/transforms/gecko_v2_whitelist.py
@@ -50,16 +50,17 @@ JOB_NAME_WHITELIST = set([
     'mulet-opt',
     'nexus-5-l-eng-debug',
     'nexus-5-l-eng-opt',
     'shell-haz-debug',
     'sm-arm64-sim-debug',
     'sm-arm-sim-debug',
     'sm-asan-opt',
     'sm-compacting-debug',
+    'sm-mozjs-sys-debug',
     'sm-msan-opt',
     'sm-nonunified-debug',
     'sm-package-opt',
     'sm-plaindebug-debug',
     'sm-plain-opt',
     'sm-rootanalysis-debug',
     'sm-tsan-opt',
     'win32-debug',

--- a/taskcluster/taskgraph/transforms/job/spidermonkey.py
+++ b/taskcluster/taskgraph/transforms/job/spidermonkey.py
@@ -12,29 +12,30 @@ from voluptuous import Schema, Required,
 
 from taskgraph.transforms.job import run_job_using
 from taskgraph.transforms.job.common import (
     docker_worker_add_public_artifacts,
     docker_worker_support_vcs_checkout,
 )
 
 sm_run_schema = Schema({
-    Required('using'): Any('spidermonkey', 'spidermonkey-package'),
+    Required('using'): Any('spidermonkey', 'spidermonkey-package', 'spidermonkey-mozjs-crate'),
 
     # The SPIDERMONKEY_VARIANT
     Required('spidermonkey-variant'): basestring,
 
     # The tooltool manifest to use; default from sm-tooltool-config.sh  is used
     # if omitted
     Optional('tooltool-manifest'): basestring,
 })
 
 
 @run_job_using("docker-worker", "spidermonkey")
 @run_job_using("docker-worker", "spidermonkey-package")
+@run_job_using("docker-worker", "spidermonkey-mozjs-crate")
 def docker_worker_spidermonkey(config, job, taskdesc, schema=sm_run_schema):
     run = job['run']
 
     worker = taskdesc['worker']
     worker['artifacts'] = []
     worker['caches'] = []
 
     if int(config.params['level']) > 1:
@@ -66,16 +67,18 @@ def docker_worker_spidermonkey(config, j
     if run.get('tooltool-manifest'):
         env['TOOLTOOL_MANIFEST'] = run['tooltool-manifest']
 
     docker_worker_support_vcs_checkout(config, job, taskdesc)
 
     script = "build-sm.sh"
     if run['using'] == 'spidermonkey-package':
         script = "build-sm-package.sh"
+    elif run['using'] == 'spidermonkey-mozjs-crate':
+        script = "build-sm-mozjs-crate.sh"
 
     worker['command'] = [
         '/home/worker/bin/run-task',
         '--chown-recursive', '/home/worker/workspace',
         '--chown-recursive', '/home/worker/tooltool-cache',
         '--vcs-checkout', '/home/worker/workspace/build/src',
         '--',
         '/bin/bash',

--- a/taskcluster/taskgraph/try_option_syntax.py
+++ b/taskcluster/taskgraph/try_option_syntax.py
@@ -159,16 +159,17 @@ RIDEALONG_BUILDS = {
         'sm-nonunified',
         'sm-arm-sim',
         'sm-arm64-sim',
         'sm-compacting',
         'sm-rootanalysis',
         'sm-package',
         'sm-tsan',
         'sm-asan',
+        'sm-mozjs-sys',
         'sm-msan',
     ],
 }
 
 TEST_CHUNK_SUFFIX = re.compile('(.*)-([0-9]+)$')
 
 
 class TryOptionSyntax(object):